Injuries to joints causing lameness commonly occur as a result of an injury or rupture of ligaments. The lameness often worsens as cartilage erosion and degenerative joint disease occurs. An example of common joint injury in human knees relate to injury or rupture of the anterior cruciate ligament (ACL) causing offset angulation of the knee joint. A similar injury in four legged animals occurs in the cranial cruciate ligament of the stifle joint. One preferred embodiment for practicing this invention can be disclosed in relation with a veterinary surgery for the stifle joint.
The cranial cruciate ligament in the stifle restrains a sliding motion of the tibia when exercising the stifle joint. A distressed or ruptured cranial cruciate ligament enables misalignment of the tibia relative to the femur thereby causing further damage of the stifle joint. Tibia plateau leveling osteotomy is a common method of treatment and taught by Barclay Slocum in U.S. Pat. No. 4,677,973 entitled “PROXIMAL, TIBIAL OSTEOTOMY FOR LEVELING A TIBIA PLATEAU” whereby an osteotomy of the proximal tibial is performed to level the tibia plateau.
Tibia plateau leveling osteotomy is not based on the mechanical or anatomic center of rotation of angulation and therefore results in caudal displacement of the weight bearing axis and a focal increase in joint force. Tibia plateau leveling osteotomy also causes caudal thrust resulting in further damage to the stifle.
Drawbacks relating to tibia plateau leveling osteotomy are addressed by a procedure known as the Center of Rotation of Angulation (CORA) based leveling osteotomy. Center of Rotation of Angulation (CORA) is the point at which proximal and distal axis intersect. When performed correctly the CORA based leveling osteotomy relieves the drawbacks related to the tibia plateau leveling osteotomy while changing the slope of the tibia plateau in the stifle joint. The CORA based leveling osteotomy additionally preserves the proximal tibial epiphysis for application of ancillary stabilizing procedures. Furthermore post operatively the CORA based leveling osteotomy establishes a preferred and stabilizing ninety degree patella tendon to tibia plateau slope angle.
Furthermore, CORA based leveling osteotomy as known in the art preserves the proximal tibial epiphysis which allows for additional stabilizing procedures, normalizing cranial thrust and producing a desired tibia plateau slope angle.
A drawback relating to the CORA based leveling osteotomy is realized during surgery due to its complexity. More specifically obtaining the desired rotation of the proximal tibia segment is challenged by forces generated by connected muscle and ligaments. Inaccurate rotation of the proximal tibia segment can further damage the stifle. These risks results in slow adoption of the CORA based leveling osteotomy.